//Code that handles click events
private void number_Click(object sender, EventArgs e)
    {
        if((txtResult.Text == "0")||(operation))
        {
            txtResult.Clear();
        }
        //Cast button to the object sender
        operation = false;
        Button button = (Button)sender;
        //If the button pressed is a "." then check if the txtResult already contains
        //a ".", if it does contain a "." then do nothing
        if (button.Text == ".")
        {
            if (!txtResult.Text.Contains("."))
            {
                txtResult.Text = txtResult.Text + button.Text;
            }
        }else
        txtResult.Text = txtResult.Text + button.Text;
    }


//Keyboard press event code

    private void num1_key(object sender, KeyPressEventArgs e)
    {
        if (e.KeyChar == '1')
        {
//If keyboard '1' pressed perform number_click()
            btn1.PerformClick();
            e.Handled = true;
        }
    }